This study is a longitudinal single-center pilot study designed to describe changes in lung function and levels of noninvasive biomarkers of airway inflammation in children ages 6-18 years over two months following hospitalization for an acute exacerbation of asthma. Forty children ages 6-18 years with asthma who are admitted to Children's Hospital and Regional Medical Center (GCRC) for an asthma exacerbation will be enrolled and complete an initial study visit prior to hospital discharge. Children with asthma will be recruited from the inpatient medical unit. During their initial visit subjects will undergo a clinical assessment and perform spirometry to measure lung function. In addition, exhaled nitric oxide (eNO) concentration will be measured and a sample of exhaled breath condensate (eBC) will be collected during 20 minutes of tidal breathing. Breath condensate will be analyzed to determine the concentration of cysteinyl leukotrienes (CysLT), an important mediator of airway inflammation in asthma. Subjects with asthma will return to the GCRC pediatric satellite at Seattle Children's Hospital for follow-up study visits at 1 week, 2 weeks, and 4 weeks following hospital discharge. During follow-up visits subjects will complete a questionnaire regarding symptoms and medication use since the most recent study visit, will perform spirometry, and have eNO concentration measured and breath condensate collected for CysLT analysis.